Process of manufacturing wood-pulp.



` lCHARLES' B. CLARK,Y OF BANGOR, MAINE.

Pnocrz'ss or MANUEACTURING ywooDPuLr.

.Specification of Letters Patent.

Patented July 13, 190e.

Application :ledV-June 12, 41907. Serial No. 378,507.

To all whom it ma'yconcem: i f 'l Be it known that I, CHARLES B.v CLARK, of Bangor, Vin the county of Penobscot and State of Maine, a citizen of the United States,

have-invented a new and useful Improve-` ment inthe Process of Manufacturin NVood- Pulp, of which the following is a fu l, clear,

and exact description, reference being had "to the accompanying drawings, forming a part of this specification, in explaining its nature. l

Myinvention relates to the manufacture of wood pulp lespecially from coniferous,

resinous or fatty ,Woods and especially also by yess.. p

The object or objects of my invention are to produce a better pulp by removing from what is ,known as the sulfite proc- 'the digester duringthe process ofcooking certain intercellular constituents ofthe Wood or extractivesl thereof which if left in the digester would tend to injure or detract from the value or quality of the pulp and the paper made from it. By these intercellular constituents or extractives` I `mean the gummy or resinous matters with other cel menting substances that bind the liber together and I shall Arefer to the same as extractive matter.` i

It is the further andeven more essential object of my invention to rovide for the reclamation or saving from t e digester of a relatively large amount of the liquor `used therein for digesting and which prior to my invention4 has been allowed to go to Waste. By my process I am enabled also to recover from the Wood extractive matter of considerable value, in which connection attention directed to my coending application for Letters Patent, Seria No. 378,506, filed June 12, l1907.

I shall describe the different phases of my invention'. or inventions in the light of the apparatus which thus far I have found-most e ectlvc 1n carrying out the process, the oonstruction and arrangement of which apparatus Ais shown diagrammatically in -the drawings.

Referring to the draWingSe-A, A1 are t-Wo digesters of ordinary construction which are adapted to become filled with chips. lThe digesters are supplied with steam by the in ets a in theusual manner. Extending from the top of each of the digcsters are pipes a. controlled by valves a2. These pipes extend from the digesters to pass first thereof.

E is an apparatus for making sulfurous through a cooler B which may be of any suitable construction. From the cooler the pipes extend to connect with a stand ipe C which connects with a storage and rec aiming Vtank D at a point preferably near vthe `bottom gas and it maybe of any known construction. pipe e with the tank F of a series of tanks F,

1, F2 and F3 in which the sulfurous gas-is mixed with limewater having preferablyfa high percentage of magnesia.` These tanks are connected with one another by a series of pipes f. The lime water by any convenient source of supply, is placed 4in the uppertank F3 from which it flows into and through .the remaining tanks of the series by means ofz the connecting pipes before mentioned. So much of the sulfurous gas as is not taken up by the lime Water in the tank F passes therefrom by the pipe f1 into the tank F2 by a connecting pipef2 Where it is absorbed.

An exhaustpump- G is connected by the pi e g With` the tank F2, which pump is a apted to establish and maintain circulation. in this part 4of the system. At this point it is tobe noted that the means shown for forming sulfurous gas and mixing it With lime Water forms no part of my invention, but is one of a number of means or methods, others of which might be employed, as is well known tot-hose versed in the art.

, The storage and reclaiming tank D is supplied Withthe combine or sulfite liquor"- from the tank F by vthe pipes d which connect With the foot of the standpipe C, which connects', as before described, with the stor age tank D.- The storage tank D is provided With any suitable vent d1. The Atank ccnnects from a point at or near its bot-tom wlth the two digesters by means of a connect-ing pipe d2 and pipes d, d3. In the pipesds, d3 are valves d4, d" for controlling the supply of liquor from the storage tank to the d1- gesters. A pumpH is .also placed in the plpe connection between the storage tank and digesters by which the supply from the storage tank may be pumped into the dlgesters. On onel side of the storage. tank there 1s formed an opening therein by which a portion of the contents of the storage tank may be drawn off. The Way which I have found the most convenient-for doing this is to control the opening in the side of the storage tank by means of a sliding gate d to which The apparatus E connects by the ressed ythat the eXtractive matter having een extracted has become so changed inv character as to injure the pulp or until it has sof Worked into the digesting liquor or be-A tive mattershould take place as early as possible in 'order to save as much of the Vgas-containing liquor as possible for the earlier the liquor is drawn off the more gas will there be .in it. To specify in hours and minutes the precise time for the free relief Would be im.-

possible inasmuch as pulp-makers carry on the digesting process for various lengths of time; some carry on a rapid process, others cook more slowly. v The period of digestion may also vary depending upon the kind of wood usedand theconditionfof the Wood may make avariat-ion in the length of time for carrying on the process of digestion. Ow-

ing, therefore, to the nature of the subject, muchof the success to be obtained from practicing applicants process will depend upon the care and skill ofthe pulp-maker. lit

might be observed, also, that thefree relief.

from the digester Will cause no undue risein ltemperature owing especially to the protracted withdrawal of .the liquor. There 'will also be no detrimental fall in the pressure owing to the fact that steam is entering the digester anchas is usually the case, the discharge pipe is smaller than the inlet pipe.

Une reason Why the constituents and eX- tractives of the Wood are especially given up during the period of the free relief is that during this period, by reason of the extracof time as vWil tion of a large amount of liquor from the digester, its contents are subjected to violent agitation by the entering steam which tends. i to disintegrate the fibers of the Wood already reduced to a condition Where-upon such agitation'the cellular incrusting and cementing matter of the Wood will bev given up freely. ln other words, during the process of the cook by drawing off a large amount of liquor from the digester I tend to cleanse the cellulose of various Woody constituents and extractivas which if left in the digester Would be injurious to the cellulose or pulp.

The time period during which the free relief of the digester continues may, of course, vary depending upon the cooking and rapidity with, Whichthe liquoris Withdrawn. i prefer that the withdrawal be such that the free relief may be 1protracted over 'such a period enable the extractive matter to be given up so as to ass out of the digestcr in the removedl iquor. `Of course this Varies depending upon the length and, intensity of the cooking.

fer the free relief to extend over a periodof` from twenty to forty-five minutes.

,I n practice I prethe free relief from-the digester the cooking lliquor is given up too freely. The tempera- After from the digester a arge amount of the constituents and extractives ofthe Wood which if left in thedigester would be injurious to the cellulose or ul and which extractive matter is in itselIf of) considerable value. I have also drawn from the digester a large amount of the gas-containing liquor which is valuable .for re-use in' the digester When clarified of the extractive matter it contains,

as may easily be done in the manner now to be described, and lWhich if leftiin'the liquor 85 would tend to seriously damage the pulp at the time of the next cook'if the liquor were re-used Without clarifying it.

Referring to the method of clarifying or freeing the liquor drawn from the digester 90. into the reclaiming tank of the eXtractive matter above referred to together with any dirt or .other foreign matter which may be' contained in the liquor, it will be understood that all the '1i uor dischargedfrom the di- 95 gester during t `e process ,of cookingl is discharged into the storage or reclaiming. tank to mingle With the fresh sulfte., liquor directed to flow therein as before described. Moreover, by means of thestandpipe the old .100 and fresh liquors 'are mixed with one another before they enter the reclaiming tank. Now l have found that When the new sulte liquor mingles with the liquor coming from the digester it facilitates the separation of the eX- 105 tractive matter from the main body of liquor in the tank causing the eXtractive matter t0 rise to the top of the liquor in the tank and leaving the' sulfite liquor below claried and in condition for re-use in the digester. The 110 separation/is also facilitated by agitation and 'especialgy if the added liquoris made dense prefera with lime or other matter notninjurious tothe digesting liquor but strengthening 4the same, as some gas-absorbing base. 115 It is also desirable if not necessaryto a successful accomplishmentL of the process that the temperature in the reclaimmgtank be not too high. `If it be too high the gas 1n the 12o ture which ihave found it most advantageous to maintain is one approximating to de 4rees F. Such temperature is secured by co iing vthe liquordischa'rgedfrom the gester and by the added liquor which 1s 125 cooler than that coming from the digester. Whileahigher temperature may be more eHective in causing a quicker separation of theextraotive matter from the-su te liquor,

it is undesirable Lfor the Areasonthatfwhen the 130 temperature approximates 100 degrees F. the sulfurous gas in the liquor begins to be given up, so in order to keep the gas in the iquor and still facilitate the separation of the 5 extractive matter contained in it I lind it desirable to maintain a temperature in the tank approximating 90 to 100 degrees F. he agitation of theliquor in the tank is caused by the pressure of the relief from the digester and in this connection it is to be observed that I prefer to direct the inflow of liquor into the bottom of the tank and in such place and direction lthat it will cause the li uor to swirl around the sides of the tank.

ith reference to securing the proper temperature in thetank, this, of course, may be done by any suitable means. I prefer, however, to do it by means'of the cooling tank, the arrangement bein such thatthe liquor having passed througlgi it when mixed with the new suliite liquor will have a temperature substantially that above referred-to.`

The arrangement for obtaining a proper temperature of the liquor assing through the cooler may be obtained y increasing or decreasing the amount of flow 'of water around the pi es. Of course in passing more water aroun the pipes of the cooler the llqior when it arrives at the reclaiming tank w' be cooler than if a lesser amount of water were4 passed around the same.

After theseparation of the extractive matter which rises to the to of the liquor in the reclaiming tank, it may e drawn oli by lowering the gate in the side of the tank when the extractiva matter will pass over the top of the ate and flow to a oint outside the tank'. gIhe level of the su tite liquor in the tank may be determined, or rather the amount of extractive matter to be drawn oli may be determined b the gage inthe side of the tank. The su te liquor being thus relieved of the eXtractive matter foreign to it may then be pumped back into the digester and used for purposes of cooking as occasion may require.

In practice I have found my process a most effective one, for the paper made from the pulp thus obtained is free from the injurious so called pitchs ots which heretofore have tended to spo it and caused la serious injury to the manufacturer by reason nof the'fact that a considerable amount of aper had to be thrown away. I-also iind t at y reclaiming a large amount of the sulfite liquor I make a very material saving in sulfur; in other words I am enabled to treat wood by the sulte process with :an amount of sulfur which has heretofore been @Q considered impossible and from an economgestively treating wood by the I claim 'and desire tosecure by Letters Patent of the `'United States 1. That improvement in the process of disullite process, so called, in a bath of digesting liquor contained in a digester to form wood pulp which consists in removing from the digester during the period of digestion an appreclable quantity of the bath containing resinous matters and extractives of the wood for the pur ose of recovering an appreciable portlon of t e bath after the'passlng of the reslnous matters and extractives into it upon a resolution ofthe Wood, and afterward continuing the process of digestionin' the liquor left in the dlgester. 2. That improvement inn the process of d1- gestively treating wood by the sulite process, so called, in bath of digesting hquor contained in a digester to form wood pulp which consists in removing from the d1gester an appreciable portion of the digesting bath at that time during the period of dlgestion when the resinous matters and extractives of the Wood are being given up to be contained in the removed portion of the bath, and afterward continuing the process of digestlon in the liquor left in the dlgester. v a 3. That improvement in the rocess of d1- gestively treating wood by the sulfite process, so called, in a bath of digestingllquor contained in a digester to form Wood pulp which consists in removing from the di .ester an a Vpreciable portion of the digesting lquor at t at time during the period of digestion When the resinous matters and extractives of the Wood are being given up most freely to pass into the digesting liquor and afterward continuing the process of digestion in the liquor left in the digester.

4. That improvement in the process of digestively treating Wood by the sulfite rocess, so called, in a bath of digesting llquor contained in a digester to form Wood pulp Which consists in removing from the digester during the eriod of digestion an appreciable ortion oft e digesting liquor after the passing of the resinous matters and extractives into it upon the resolution of the Wood and while such resinous matters and extractives are separable from said removed liquor, and afterward continuing the process ofl digestion in the liquor left in the digester.

5. .That improvementin the process of di gestively treating Wood by the sulte process in a hot bath of ,-'digesting liquor contained in a ndigester to ,form woodpulp which consists in removing'from the lgester an appreciable portion of the digesting liquor at that time during the period of digestlon when the resinous matters and extractions of the Wood arefreely being given u into the removed portion of the ath and before their character has become changed by their cooking long in the hot bath or have to pass become soluble therein, and afterward continuing the process of digestion in the liquor left in the digester.

6. That improvement in the process of digestively treatin Wood bythe sultite proces's in a bath o digesting liquor. contained in a digester to form Wood pulp which consists in digestively treating the wood until the digesting liquor in the main` body of the digester beginsl to become changed in color by the resinous matters and extractives of the Wood passing into the liquor,then removing from the digester an appreciable portion of the liquor therein containing rcsinous matters and extractivas, the removal to continue for a protracted interval of time, and afterward continuing the process of digestion in the liquor left in the digester.

7. That improvement in the process of digestively treating Wood by the sulfite process in a bath of digesting liquor contained in a digester to form Wood pulp which consists in relieving the digester to obtain therein proper degrees of heat and pressure for digesting until the digesting liquor begins to receive the extracted resinous matters and extractives of the wood as may be noted by the changing color of the liquor, then removing from the digester at the top thereof an appreciable. portion of the liquor therein con-l taining extracted resinous matters and extractives, the removal ofthe liquor from the digester to continue for a. protracted interval ci timeaand afterward continuing the process of digestion in the liquor left in the digester'.

8. That improvement in the process oi digestively treating wood by the' sulite process. in a .bath of digesting liquor contained in a digester to form Wood' pulp Which consists in removin from the digester an appreciable portion oV the liquor therein when the liquor in the body of the digester begins to turn amber color, the removal of the liquor to continue for a protracted interval of time or until the amber-colored liquor becomes dark iii color, and afterward continuing the rocess of digestion in the liquor left in the ives from this saved liquor.

14. That improvement in the process of 9. 'liiat improvement in the process of digestively treating wood by the sulite process so called, in a bath of digesting liquor contained in a digester to form wood pulp Whichconsists in s owly raising the temperature of' the. digester until the temperature therein approximates 290? F., then removing an appreciable quantity of liquor from the j digester, the removal of liquorto continue for a protracted interval of time, and after- Ward continuing the process of digestion in the liquor left in the digester. g.:

10. That improvement in the process'of dil gestively treating Wood by the sulfite 'proce'ss in a bath of digesting li uor contained in a digester to^form Wood pu which 'consists in a continuation of the process until the rese tinuing the process in the liquor left in the digester and venting the digester as occasion may require. i

1 1 That improvement in the process of digestively treating Wdod by the suliite process, so called, ina bath of digesting liquor contained in a digester to form Wood pulp which consists in removing from the digester during the period of digestion a portion of the digesting liquor containing resinousmatters and extractivas of the wood separable from the removed liquor, directing the removed liquor to a suitable receptacle and separating the resinous matters and extractives therefrom.l

12. That improvement in the process of digestively `treating Wood bythe sulte process, so called, in a bath of digesting 'quoi' contained in a digester to form Wood pulp which consists in saving by directing to a suitable lreceptacle gas-containing liquor discharged from the digester during the eriod of digestion, which liquor contains a so resinous matters and extractives of the wood separable from said liquor, and afterward separating the resinous matters and extracti ives from this saved liquor.

13. That improvement in the process di" digestively treating Wood by the sulfite rocess, so called, in a bath of digesting iquor contained in a digester to form Wood pulp which consists in saving by directing to a suitable receptacle gas-containing liquor discharged from the digester at that time during the period of digestion when the resinous'matters and extractives of the Wood are freely assing into the digesting nliquor upon a reso ution of the Wood, and lafterward separating the resinous matters yand extractiio digestively. treating wood bythe sulfite ing liquor ait-that time during the period of digestion when the resinous matteis and extractives of the Wood are freely being given up to pass into they removed portion ed: the liquor and before their character has beeoine changed by their cooking long the liquor for have become soluble therein, directing the removed liquor to a suitable receptacle and vseparating the. resinoiis matters and extractives therefrom.

15. That improvtlinztheprucess of `ing digestively treating wood by the sulfite recess" so called, in a bath of digesting iquor contained in a digesterl to form Wood pulp which consists in saving by directing to a receptacle gas-containing liquor discharged fromthe digester during the period of digestion which contains resinous matters and eX- tractives separable from said liquor, separate the resinous 'matters and extractives from the saved liquorby adding other liquor 16. That improvement'in the process of ydigestively treating Wood by the sulfite recess, sc called, ina bath. of digesting iquor contained in a digesterv to form Woo'd pulp which consists in saving by directing to a receptacle gas-containing liquor'discharged from the .di ester ,during the period of digestion which iquor contains resinous matters and extractives. separable from said liquor, separating the resinous matters and extractives from the saved liquor by adding thereto is; liquor made dense with a gas-absorbing ase.

17. `That improvement in the process of digestively treating Wood by the sulite rocess'f, so called, in a bath of 'digesting iquor contained in a digester toform Wood pulp which consists in removing from the digester an applreciable portion of the digesting liquor at t at time lduring the period of digestion when the resinous matters and eX- ltractives of the Wood are freely being given upto passinto the removed portion of the -bath and before their character has vbecome changed by their cooking long in the'bath or have become solubletherein, separating the resinous matters and extractives from-the removed liquor byv adding to it fresh liquor.

18. That improvement inthe process of the sulflte process, yso called, in a bath of digestin 1quor contained in a digester to form Woo pulp which consists in .removing from the digester during the period of digestion a portion of the digesting liquor containing resinous matters and -extractives of" the wood separable from the removed liquor, cooling the removed liquor directed to a suitable receptacle and separating the resinous matters andextractives therefrom.

19. That improvement in the process of digestively treating wood by the sulfite the process, so called, in a bath of digesting rliquor contained in a digester to form Wood pulp which consists in saving by directing to a suitable receptacle gas-containing liq-j uor discharged from the digester during thev 'liquor contained in al digester to form woo period of digestion, which liquor contains` also resinous matters and extractives of the Wood Aseparable from saidl liquor, cooling the saved liquor and afterward separating f resinous matters and-extractives thererom.

'digestively treating woody by 20. That improvement in the process ofV digestively treating '.wood by :the sulfite rocess, so called, in a bath of digestingiquorcontained in a digester to form Wood pulp which consists in saving by directing to a suitable receptacle gas-containing liquor discharged from the digester at that time during the period of digestion when the` resinous matters and eXtractives of the Wood are freely passing into the digestinnliquor upon a resolution of Athe Wood, coo g the saved liquor and, afterward separating the resinous matters and extractives therefrom.

21. That improvement in the process of digestively treating Wood by the .sulfite rocess, so called, in a bath of digesting lquor contained in a digester to form Wood gulp which consists in removing from the igester ana reciable ortion ofthe digest- Pll P ing liquor at t at time during the period of digestion when the resinous matters and extractives of the Wood are freely being given up to pass. into the removed portion4 of the liquor andv before' their character has become changed by their cooking y long in the liquor or have become soluble therein, cooling the removed liquor directed to a suitable receptacle and separating the resinous matters and extractives therefrom.

22. That improvement in the-processo'f digestively treating wood by the` sulfite rocess, so called, in' a bath of digesting quoi` contained in a digester to form Wood gulp which consists in removing from the igester during the period of dlgestion an appreciable portion of the digesting vliquor containing resinous matters andextractives of the Wood .se arable from the removed liquor, cooling the removed liquor directed resinous matters and extractives from the removed liquor by adding other liquor thereto. f

23,.,That improvement in the process of process, so called, in a-bath of digesting 'quor contained in a digester to form wo pulp -Which consists in saving bi to a receptacle gas-containing lquor discharged from the digester during the'period of digestion which contains resinous matters and extractives se arable .from said liquor, cooling4 the save liquor. and Vafterward separating the resinous'mattersand extractives therefrom by uor thereto. l.

24. That improvement in the process of digestively treating wood by the fsulfite process, so called, in a bath of dlgestm the sulfitel adding other liq- 1 to a'suitable receptacle and lseparating the directing When-the resinous matters and exl ltractives ofthe vWoodoare freely bein given removed lquor,

cooling the removed liquor directed to a suitable receptacle and separating the resinous matters and extractives from the removed liquor by adding to it other liquor for facilitating s uchseparation.

25.- 4That improvement in the process of digestively treating Wood by the sulte roc-ess, so called7 in a bath of digesting iquor contained in a digester to form Wood pulp which consists in removing from the digester an appreciable portion of the digest-v ing liquor at that time during the period of Ydigestion When the resinous matters and eX- tractives of the Wood are freely being given upto pass into the removed portion of the bath and before their character has become changed by their cooking long in the bath or have become soluble therein, cooling the removed liquor directed to a suitable recepf tacle and afterward separating the resinous matters and extactives therefrom by adding to the removed liquor fresh liquor.

l2,6. That improvement inthe process of digestively treating wood by the sulite rocess, so called, in a bath of digesting iquor contained in a digester tov form wood pulp which consists in removing from the4 -or have become soluble therein, cooling the removed liquor directed to a suitable recep- -tacle and afterward, separating the resinous matters and extractives therefrom by adding fresh liquor thereto directed to flow into said receptacle and rendering ,the tempera-v ture of the combined liquors in the reseptacle approximately 90 to 100 degrees F.

CHARLES B. CLARK. Witnesses:

JOHN E. R. HAYES, M. V. FOLEY. 

